Free and Open Source Invoicing, Expenses & Time-Tracking
Free Invoice & Billing Software for Windows, Linux & Mac
ERP Server
Fullstack open source Invoicing application made with MongoDB
Free & Open Source Invoice App for Freelancers & Small Businesses
Invoice and office utilities program for customer managment
Intuitive quote, delivery note, invoice, payments management app
Keep track of all your job costs, make sure you don't lose money